diff --git a/configure b/configure
index c1819fff..5667f078 100755
--- a/configure
+++ b/configure
@@ -3753,6 +3753,9 @@ then :
 
 fi
 
+sodium_CFLAGS=${CFLAGS+set}
+: ${CFLAGS=""}
+
 
 
 
@@ -5289,6 +5292,206 @@ fi
 
 
 
+if test "$sodium_CFLAGS" != "set" ; then
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts -Ofast" >&5
+printf %s "checking whether C compiler accepts -Ofast... " >&6; }
+if test ${ax_cv_check_cflags___Ofast+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  -Ofast"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <time.h>
+int
+main (void)
+{
+time_t x; int fodder = 0; if (fodder > -1000 && time(&x)) return (int) x
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ax_cv_check_cflags___Ofast=yes
+else $as_nop
+  ax_cv_check_cflags___Ofast=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ax_cv_check_cflags___Ofast" >&5
+printf "%s\n" "$ax_cv_check_cflags___Ofast" >&6; }
+if test "x$ax_cv_check_cflags___Ofast" = xyes
+then :
+  CFLAGS="$CFLAGS -Ofast"
+else $as_nop
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts -O3" >&5
+printf %s "checking whether C compiler accepts -O3... " >&6; }
+if test ${ax_cv_check_cflags___O3+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  -O3"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <time.h>
+int
+main (void)
+{
+time_t x; int fodder = 0; if (fodder > -1000 && time(&x)) return (int) x
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ax_cv_check_cflags___O3=yes
+else $as_nop
+  ax_cv_check_cflags___O3=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ax_cv_check_cflags___O3" >&5
+printf "%s\n" "$ax_cv_check_cflags___O3" >&6; }
+if test "x$ax_cv_check_cflags___O3" = xyes
+then :
+  CFLAGS="$CFLAGS -O3"
+else $as_nop
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts -O2" >&5
+printf %s "checking whether C compiler accepts -O2... " >&6; }
+if test ${ax_cv_check_cflags___O2+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  -O2"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <time.h>
+int
+main (void)
+{
+time_t x; int fodder = 0; if (fodder > -1000 && time(&x)) return (int) x
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ax_cv_check_cflags___O2=yes
+else $as_nop
+  ax_cv_check_cflags___O2=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ax_cv_check_cflags___O2" >&5
+printf "%s\n" "$ax_cv_check_cflags___O2" >&6; }
+if test "x$ax_cv_check_cflags___O2" = xyes
+then :
+  CFLAGS="$CFLAGS -O2"
+else $as_nop
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts -O1" >&5
+printf %s "checking whether C compiler accepts -O1... " >&6; }
+if test ${ax_cv_check_cflags___O1+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  -O1"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <time.h>
+int
+main (void)
+{
+time_t x; int fodder = 0; if (fodder > -1000 && time(&x)) return (int) x
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ax_cv_check_cflags___O1=yes
+else $as_nop
+  ax_cv_check_cflags___O1=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ax_cv_check_cflags___O1" >&5
+printf "%s\n" "$ax_cv_check_cflags___O1" >&6; }
+if test "x$ax_cv_check_cflags___O1" = xyes
+then :
+  CFLAGS="$CFLAGS -O1"
+else $as_nop
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts -O" >&5
+printf %s "checking whether C compiler accepts -O... " >&6; }
+if test ${ax_cv_check_cflags___O+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+
+  ax_check_save_flags=$CFLAGS
+  CFLAGS="$CFLAGS  -O"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <time.h>
+int
+main (void)
+{
+time_t x; int fodder = 0; if (fodder > -1000 && time(&x)) return (int) x
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ax_cv_check_cflags___O=yes
+else $as_nop
+  ax_cv_check_cflags___O=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+  CFLAGS=$ax_check_save_flags
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ax_cv_check_cflags___O" >&5
+printf "%s\n" "$ax_cv_check_cflags___O" >&6; }
+if test "x$ax_cv_check_cflags___O" = xyes
+then :
+  CFLAGS="$CFLAGS -O"
+else $as_nop
+  :
+fi
+
+fi
+
+fi
+
+fi
+
+fi
+
+fi
+
+
 # Check whether --enable-ssp was given.
 if test ${enable_ssp+y}
 then :
@@ -6869,46 +7072,6 @@ then :
   if test "x$enableval" = "xyes"
 then :
 
-    { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts -Ofast" >&5
-printf %s "checking whether C compiler accepts -Ofast... " >&6; }
-if test ${ax_cv_check_cflags___Ofast+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-
-  ax_check_save_flags=$CFLAGS
-  CFLAGS="$CFLAGS  -Ofast"
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <time.h>
-int
-main (void)
-{
-time_t x; int fodder = 0; if (fodder > -1000 && time(&x)) return (int) x
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"
-then :
-  ax_cv_check_cflags___Ofast=yes
-else $as_nop
-  ax_cv_check_cflags___Ofast=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam \
-    conftest$ac_exeext conftest.$ac_ext
-  CFLAGS=$ax_check_save_flags
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ax_cv_check_cflags___Ofast" >&5
-printf "%s\n" "$ax_cv_check_cflags___Ofast" >&6; }
-if test "x$ax_cv_check_cflags___Ofast" = xyes
-then :
-  CFLAGS="$CFLAGS -Ofast"
-else $as_nop
-  :
-fi
-
     { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts -ftree-vectorize" >&5
 printf %s "checking whether C compiler accepts -ftree-vectorize... " >&6; }
 if test ${ax_cv_check_cflags___ftree_vectorize+y}